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Introduction

Resource Description Framework (RDF) is one of the most exciting new
standards to emerge from the World Wide Web Consortium (W3C)the people who
gave us XML. It's also the most widely misunderstood topic since XML
itself. That's because RDF is all about metadata, and metadata is a
slippery topic. In my book XML and SQL: Developing Web Applications
(publication details below), I describe an approach (called partial
decomposition) to extracting metadata from XML documents and storing this
metadata in SQL databases.

I remember getting feedback from a technical reviewer saying that I had
misunderstood the term metadata. This reviewer felt that metadata
represented things like field lengths (such as 160 bytes) and datatypes (string,
integer, etc.). The reviewer was rightin the context familiar to him or
herbut didn't understand that metadata can have another context: a
content-centric context.

If you're familiar with XML, you know that XML isn't actually a
markup language in and of itself. XML is a framework for creating
markupit's a set of markup "rules to live by." RDF is the
same kind of animal as XML. It isn't a metadata standardit's a
way to build metadata standards and a standard way to represent metadata in XML
form. RDF stands for Resource Description Framework, and it's just
that: a framework that can be used in many different contexts to achieve many
different goals.

RDF goes one step beyond a standard representation of metadata. RDF is
self-describing metadata. Used properly, RDF metadata can describe itself to
whomever happens to be listening.